Sectos NXA
Switch disconnector for overhead networks
General
The NXA is a SF6 -insulated pole mounted switch disconnector suitable for both
conventional overhead lines and BLX type lines with insulated conductors and specifically
designed for use in modern tele-controlled distribution automation systems. The NXA offers
reliable maintenance free operation even in the most demanding climatic conditions
including salt laden atmospheres, corrosive industrial pollution, snow and ice.
Switch design
The three phase switch unit is mounted inside a sealed for life stainless steel tank filled
with a small SF6 overpressure. The stainless steel tank is designed specifically to guarantee
the safety of the operation personnel even with the internal arc faults at the maximum fault
capacity. Due to high internal arc containment capacity of the tank the NXA in most cases
withstands an internal fault without venting hot gases. The independent spring operating
mechanism provides a guaranteed load break fault make capability by ensuring the opening
and closing speed of the switch.
The NXA is provided with a standard SF6 gas density indication unit ensuring guaranteed
lightning impulse withstand voltage rating and maximum reliability when used as a point
of isolation.
Installation
The switch is suitable for horizontal mounting either above or below the crossarm.
A selection of different mounting equipment is also available.
Control
The switch can be manually controlled or it can be provided with an integrated motor
drive for both tele and/or local electrical control. The motor drive can easily be retrofitted
on site to manually operated units. Both manual operation and mechanical locking (when
fitted) are by hook stick with local electrical operation at ground level (when required)
via a control box. Hook stick operation negates the need for the provision of an operator
earth mat.
Position indication
The NXA is provided with light reflecting position indicators which are directly connected
to the switch operating shaft providing clear and unambiguous switch position indication.
When manual switch locking is required half eyelid indication over the position indicator
is provided.
Position indicating contacts directly connected to the operating shaft are provided to
give remote switch position indication via the RTU to the telecontrol system.
Insulators
The NXA is provided with standard 400 series outer cone bushings fitted with silicone
rubber insulators. Silicone rubber insulator is suitable for line termination with standard
cable lugs. Outer cone bushings are also suitable for standard elbow type cable connectors.
A wide range of current transformers suitable for overcurrent and earth fault protection
are available for mounting around the bushings.
Remote control
The NXA can be provided with a stainless steel pole mounted
control box sealed to IP54 and incorporating:
• 24 VDC battery and charger
• Open/Close Remote/Local Control
• Battery monitor device
• VT Supply fail
• RADIO & RTU (to customer
approved standards)
• Earth fault passage indicator
• Auto sectionalizing
One control box can control up
to four NXA switches.
955
1286
700
669
ø 14
669
24
507
M16
Z
Sectos NXA switch disconnector complies with the IEC 60265-1 (1998)
requirements for General purpose switches in electrical endurance class E2 and
mechanical endurance class M2. The breaking tests under earth fault conditions
enable use also in isolated or resonant earthed neutral systems.
Ratings
NXA 36
_______________________________________________________________________________________________________________
Insulation level
_______________________________________________________________________________________________________________
___________Rated
______________________voltage
__________________________________________________________________________________________________________________________________________________________________________________________________________________________________kV
____________________________________________36
______________________________
Power-frequency
withstand
voltage,
60
sec
wet
______________________________________________________________________________________________________________________________________________________________________________________________________________________________
kV
– to earth and between phases
70
_______________________________________________________________________________________________________________
kV
– across isolating distance
80
_______________________________________________________________________________________________________________
Lightning impulse withstand voltage
_______________________________________________________________________________________________________________
______________–_______to
______earth
______________and
__________between
______________________phases
____________________________________________________________________________________________________kV
_____________________________170
____________________
kV
– across isolating distance
195
_______________________________________________________________________________________________________________
Mainostoimisto WILMA / Waasa Graphics Oy, 2002-04. Printed in Finland.
Technical specification
_______________________________________________________________________________________________________________
Current ratings
_______________________________________________________________________________________________________________
Electrical endurance class
E2/E3
_______________________________________________________________________________________________________________
A
Rated normal current
630
_______________________________________________________________________________________________________________
A
Mainly active load breaking current
630
_______________________________________________________________________________________________________________
Number of breaking operations CO
400
_______________________________________________________________________________________________________________
A
Closed loop breaking current
630
_______________________________________________________________________________________________________________
A
Line- and cable-charging breaking current
40
_______________________________________________________________________________________________________________
A
Earth fault breaking current
175
_______________________________________________________________________________________________________________
Cable-charging breaking current
_______________________________________________________________________________________________________________
A
under earth fault conditions
80
_______________________________________________________________________________________________________________
A
No-load transformer breaking current
20
_______________________________________________________________________________________________________________
_______________________________________________________________________________________________________________
Short-circuit ratings
_______________________________________________________________________________________________________________
Electrical endurance class
E2/E3
_______________________________________________________________________________________________________________
kA
Short-time withstand current Ik (3 s)
16
_______________________________________________________________________________________________________________
kA
40
Peak withstand current, Idyn, peak
_______________________________________________________________________________________________________________
kA
40
Short-circuit making current
_______________________________________________________________________________________________________________
3/5
Number of making operations
_______________________________________________________________________________________________________________
ABB Oy
Medium Voltage Technology
P.O.Box 613, FIN-65101 Vaasa, Finland
Phone +358 10 22 11
Fax
+358 10 22 44661
www.abb.com
NXA 11 GB 02-04
IPX7
Degree of protection (Top motor box)
_______________________________________________________________________________________________________________
mm
1440
Creepage distance of insulators
_______________________________________________________________________________________________________________
5000
Mechanical endurance (number of close - open operations)
_______________________________________________________________________________________________________________
-40 °C...+60 °C
Ambient air temperature limits
_______________________________________________________________________________________________________________
bar (abs)
Filling pressure (+20 oC)
1.5
_______________________________________________________________________________________________________________
kg
99
Weight